As a technique used in intake apparatuses for supplying intake air to an internal combustion engine, the exhaust gas recirculation (EGR) technique for mixing part of exhaust gas, exhausted from an internal combustion engine, into intake air and recirculating the exhausted gas mixed into the intake air so as to achieve reduction of nitrogen oxide contained in the exhaust gas is used. When mixing the EGR gas with the intake air, it is desirable to sufficiently mix the EGR gas with the intake air (fresh air). Thus, various techniques for promoting mixing have been proposed. For example, Japanese Unexamined Patent Application Publication No. 10-196466 discloses a device in which a premixing chamber is provided, and Japanese Unexamined Utility Model Registration Application Publication No. 3-73649 discloses a device in which a partition plate having a plurality of holes is provided at an outlet port of EGR gas so as to distribute the EGR gas.
On the other hand, in order to solve the problems with these devices, such as the complicated shape of the intake manifold and the increased size, an intake apparatus has been proposed in which an air connector having a deflecting part for deflecting a main flow of intake air introduced from a common intake air introducing pipe is formed continuously at an end of a surge tank in a cylinder arrangement direction, and an EGR pipe is open to the inside of the air connector such that the flow of EGR gas promotes deflection of the main flow by the deflecting part (see Japanese Unexamined Patent Application Publication No. 2009-203920).
However, even in the intake apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2009-203920, since the air connector and the opening for the EGR gas are arranged at the end of the surge tank in the cylinder arrangement direction, the EGR gas may not be uniformly distributed to a plurality of cylinders. Further, promotion of deflection of the intake air by the EGR gas flow, in turn, generates a vortex in the intake air to promote mixing, but the vortex reduces the flow rate of the intake air. Then, the intake efficiency may be reduced, and EGR gas may not be sufficiently mixed with the intake air.